First Report of Curvularia hominis as a Causal Agent of Riceberry Rice Leaf Spot in Northern Thailand

Abstract

L eaf spot disease was observed on Riceberry rice (Oryza sativa L.) in the San Pa-Tong District of Chiang Mai Province, northern Thailand during the rainy season in September 2015. A single strain of Curvularia was isolated from disease symptoms. To confirm its pathogenicity, the isolated fungus was used to inoculate healthy Riceberry rice leaves. Subsequently, the same fungus was re-isolated from the leaves, displaying similar symptoms to those observed in the field. Morphological characteristics and multi-gene phylogenetic analyses of the internal transcribed spacers (ITS) and large subunit (LSU) of nuclear ribosomal DNA, glyceraldehyde-3-phosphate dehydrogenase (GPDH), and the RNA polymerase II second largest subunit (RBP2) genes were applied to identify the pathogen as Curvularia hominis. This finding represents the first report of C. hominis as the causal agent of leaf spot disease on Riceberry rice in Thailand.